Arrangement for a transparent covering element with an electrochromatic layer

ABSTRACT

A covering element consisting of transparent material is designed with an electro-chromatic layer for control of the transmission of light through the covering element. An electrical power which is required for control of the electro-chromatic layer is obtained from a photo-electric layer integrated in the covering element. The photo-electric layer is arranged outside the electro-chromatic layer. By means of the arrangement, when the light is at its most intensive, a high voltage is obtained from the photo-electric layer and can be transferred to the electro-chromatic layer so as to in this connection reduce, at least to a considerable extent, the transmission through the covering element. The arrangement can, within vehicle technology for example, be used in a sun-roof in order to prevent heating up of an interior space in sunny weather. By means of the arrangement, the transmission is automatically adapted according to the light. The arrangement also leads to the complete elimination of the risk that the vehicle battery will be discharged, since all the energy which is supplied to the electro-chromatic layer is generated in the photo-electric layer.

BACKGROUND OF THE INVENTION

The present invention relates to an arrangement for a covering elementmade from an at least partially transparent base material, whichcomprises an integrated electro-chromatic layer for electrical controlof the light transmission through the covering element.

It is previously known, in different connections, to design glass sheetsand other transparent covering elements with electro-chromatic layers,by means of which the light transmission through the glass sheet can becontrolled. In this connection the electro-chromatic layer usuallycomprises two electrically conductive layers, which surround on bothsides an ionically conductive layer. By means of exposing the ionicallyconductive layer, via the electrically conductive layers, to differentelectrical voltage fields, the light transmission can be controlledthrough the ionically conductive layer and thus through the wholecovering element also. The electrical voltage necessary for the controlis usually obtained from a per se conventional voltage source. Accordingto what is stated, for example, in the American patent specificationU.S. Pat. No. 4,240,021 which relates to a solar-cell powered clock, abattery can also be used as a voltage source. In this case, inside theelectro-chromatic layer, a number of photocells are arranged, whichconvert the light incident on them into electrical power in order tocharge a battery. Since the electro-chromatic layer is arranged outsidethe photocells, it is possible to control the light incident on thephotocells and thus control the electrical power emitted from thephotocells. This is used in order to prevent overloading of the batterywhich is connected to the photocells.

As far as vehicles are concerned, use has been made of electro-chromaticlayers in windscreens and other covering elements only in certainprototype cars. The intention in this case is among other things to beable, in sunny weather, to prevent too much sunlight shining into anarea to be irradiated by the sunlight, such as, the interior space ofthe vehicle and thus the associated increase in temperature. This can,however, principally be used during operation of the vehicle whensufficient power is obtained from the generator of the vehicle. Thepossibilities of preventing an increase in the temperature of theinterior space during a long parking time, for example, are limited bythe power which is stored in the battery of the vehicle. If parkingcontinues for too long, there is a risk that the battery will bedischarged and that as a result of this the vehicle cannot be started.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome this disadvantage ofknown solutions. The invention thus relates to an arrangement whichpermits the sun shining into a vehicle to be reduced by means of anelectro-chromatic layer in one or more of the covering elements of thevehicle, even when the vehicle is parked for a long time, without therisk of the normal battery of the vehicle being discharged.

This object is achieved according to the invention by a covering elementcomprising an electro-chromatic layer and an integrated photo-electriclayer, outside of the electro-chromatic layer, which converts the lightincident on the photo-electric layer into electrical power, and by thephoto-electric layer being electrically connected to theelectro-chromatic layer and supplying the same with electrical power inproportion to the light which is incident on the photo-electric layer,by means of which the transmission through the covering element iscontrolled automatically depending upon the incident light.

The arrangement according to the invention permits the electrical powerwhich is required for control of the electro-chromatic layer to besupplied from a separate power source. The electrical power, which issupplied from the photo-electric layer, is proportional to the incidentlight, which means that the power supply is greatest when the demand isgreatest. In this manner, automatic adaptation of power supply anddemand is achieved. Furthermore, the integrated construction of anelectro-chromatic layer together with a photo-electric layer in thecovering element means that a compact and simple construction isobtained.

BRIEF DESCRIPTION OF THE DRAWING

Further features and advantages characterizing the invention emerge fromthe attached description of an exemplary embodiment of the invention.The description is carried out with reference to the attached drawing,in which

FIG. 1 shows a cross section of a covering element according to theinvention and a basic wiring diagram showing how different layers in thecovering element are connected to one another.

DESCRIPTION OF A PREFERRED EMBODIMENT

The attached FIG. 1 shows a cross section of a covering element for avehicle, for example a passenger car with a closed body. In thisexample, the covering element is constituted by a sun-roof 1, which isarranged in the roof of the vehicle and which can be opened in order toventilate the interior space contained within the vehicle. The sun-roof1 is designed with a frame, in which mechanical elements are fixed forfixing and manoeuvring of the opening and closing of the sun-roof. Thisframe and the mechanical elements associated with it are designedentirely according to conventional technology and are thus not describedfurther.

The attached FIG. 1 shows a cross section of a part of the sun-roof 1.The lowest part of the sun-roof 1, which corresponds to that part of thesame which lies innermost towards an area to be irradiated by sunlight,i.e., the interior space, is made of glass 2. Above this, the sun-roof 1comprises an integrated electro-chromatic layer 3-7, which consists of anumber of film layers arranged one upon the other. The following can begiven as an example of how the electro-chromatic layer 3-7 isconstructed. At the bottom and against the glass 2, a layer of atransparent conductor 3 is arranged, which consists of indium tin oxide(ITO). Successively arranged above this are a counter-electrode 4 madeof molybdenum hydroxide MOH, an ionic conductor 5 made of tantalum oxideTaO, an electro-chromatic electrode 6 made of tungsten oxide WO3 and, atthe top, a transparent conductor 7 made of indium tin oxide ITO.

Above the electro-chromatic layer 3-7 an insulating plastic film 8 isarranged, on top of which an integrated photo-electric layer 9-11 isarranged. On the outside, the photo-electric layer 9-11 is covered withglass 12. The photo-electric layer 9-11 also consists of a number ofdifferent film layers. In this example, the photo-electric layer 9-11consists of two film layers of a transparent conductor 9, 11 made ofindium tin oxide ITO, between which a thin film layer of an ionicconductor 10 made of silicon material is arranged. In alternativeembodiments, it is possible to select other materials and designs of therespective layers. However, as with the layers indicated, types shouldbe selected which are transparent to a greater or less extent. This initself does not exclude the possibility that completely non-transparentmaterials can also be used, but these must then be positioned so that atleast certain parts of the sun-roof 1 can be considered transparent.

The transparent conductors 3, 7, 9, 11, which constitute thephoto-electric layer 9-11 and the electro-chromatic layer 3-7, areconnected to one another according to the wiring diagram which isschematically reproduced in FIG. 1. The transparent conductors 3, 7, 9,11 in both layers are connected to an electrical control unit 13. Alsoconnected to the control unit 13 is an electrical sensor 15 which sensesthe temperature in the area to be irradiated by the sunlight, i.e.,interior space of the vehicle and transmits a signal, which correspondsto this, to the control unit 13. The physical positioning of this sensor15 can be varied to a large extent and can, for example, be combinedwith an already existing sensor which forms part of the ventilationsystem of the vehicle. It is also possible to design the sensor 15 as aseparate sensor, which is built into the frame, which surrounds thesun-roof 1, or close to it in the roof of the vehicle.

The control unit 13 is designed to form the link between the respectiveconductors 3, 7 and 9, 11 of the two layers 3-7 and 9-11 respectivelyunder certain normal operating conditions. Under these conditions, thesensor 15 has no effect in any way. In a simplified form of theinvention, therefore, the control unit 13 can be replaced with aconnecting wire.

The light incident on the outside of the sun-roof 1, and indicated bythree arrows 16 in the FIG. 1, passes, without appreciable hindrance,through the protective outer glass 12. In the photo-electric layer 9-11,there takes place in the ionically conductive layer 10 a flow of ions,which sets up a voltage between the two conductors 9, 11, which voltageis proportional to the incident light 16. The control unit 13 transfersthis voltage to the electro-chromatic layer 3-7, that is to say thevoltage is applied via the transparent conductors 3, 7 between theelectro-chromatic electrode 6 and the counter-electrode 4. The result ofthis is that the ionic conductor 5, which lies between them, changes, inproportion to the voltage which is applied, its transmission capacityfor light passing through. The transmission is in this connectionreduced in proportion to an increase in the voltage.

By means of the arrangement, with strong sunlight, a high voltage isobtained from the photo-electric layer 9-11 and is transferred to theelectro-chromatic layer 3-7 in order to completely or to a considerableextent prevent the passage of the light 16 through the sun-roof 1. Theheating up of the interior space which occurs in the summertime as aresult of sun shining in can be reduced considerably by these means. Thecontrol of the light transmission through the sun-roof 1 is thuseffected completely automatically and simply, depending upon theincident light 16.

The temperature sensor 15, which is arranged in the interior space, isused under certain conditions to modify the described functioning. Thecontrol unit is designed so as to control the voltage transmittedbetween the conductors 3, 7, 9, 11 of the two layers 3-7, 9-11,depending upon the parameter value representing the variable quantity,the interior temperature. The temperature sensor 15 is in thisconnection used, in the event of low interior temperatures, to reducethe voltage which is transferred via the control unit 13 to theelectro-chromatic layer 3-7. In the wintertime, for example, when theinterior temperature can assume a low value during parking, there is noneed to exclude the sunlight.

The invention can be modified within the scope of the attached claimsand designed otherwise than in the manner indicated in the exampledescribed. In addition to the exemplary temperature sensor 15, a sensor14, which senses another variable quantity in the interior space, forexample the light incident on the interior space, can also be connectedto the control unit 13. Likewise, the control unit 13 can be connectedto a manually operable control device, by means of which thetransmission through the sun-roof 1 can be manually controlled. Thecontrol unit 13 can also be connected to another voltage source (notshown) so as to render control possible also, in a manner known per se,when the power supplied from the photo-electric layer 9-11 is too low.Preferably, the other voltage source should be designed to supply powerprincipally when the vehicle is in operation. It is thus possible, whendriving at night, for dazzling light to be excluded from the interiorspace. The example described relates to a sun-roof 1, but the inventioncan advantageously be applied to other covering elements within vehicletechnology such as windscreens, rear windows, side windows or completeroofs of transparent material.

In the example described general expressions such as light and sunlightare used, with which electromagnetic radiation mainly within and in thevicinity of the entire visible spectrum is principally intended. Inalternative embodiments, the invention can be used to control thetransmission of radiation within other intervals of the spectrum, bothinside and outside the visible range. With regard to the fact that it isto a large extent longwave radiation which conveys heat, it may incertain cases be sufficient to control with regard to this. Furthermodifications are also possible within the scope of the inventive idea,both within the area of vehicles and other technical areas.

I claim:
 1. A covering element adapted for automatically controlling the transmission of incident electro-magnetic radiation through the covering element dependent upon the electro-magnetic radiation incident upon the covering element, the covering element comprising:an electro-chromatic layer for electrically controlling transmission of electro-magnetic radiation through the covering element to an area to be irradiated by the electro-magnetic radiation, the electro-chromatic layer having an outside which faces the incident electro-magnetic radiation and having an opposite inside which faces toward the area and also having means which are adapted to vary the transmission of electro-magnetic radiation through the electro-chromatic layer dependent upon an electric energy supplied to that layer; a photo-electric layer at the outside of the electro-chromatic layer, the photo-electric layer being adapted for transmitting electro-magnetic radiation and for converting some of the electro-magnetic radiation that is incident on the photo-electric layer into electric energy; means electrically connecting the photo-electric layer to the electro-chromatic layer for supplying the electro-chromatic layer with electric energy that is proportional to the electro-magnetic radiation which is incident on the photo-electric layer, for causing the electro-chromatic layer to automatically control the transmission of electro-magnetic radiation through the electro-chromatic layer and the covering element, dependent upon the incident radiation.
 2. The covering element of claim 1, further comprising an electrical control unit for controlling the electric energy supplied to the electro-chromatic layer.
 3. The covering element of claim 2, further comprising a sensor for sensing a variable parameter in the area that is covered by the covering element, which parameter is dependent upon the amount of electro-magnetic radiation that is incident on the covering element; andmeans connecting the sensor to the electrical control unit for enabling the electrical control unit to vary the electric energy supplied to the electro-chromatic layer, dependent on the variation in the parameter.
 4. The covering element of claim 3, wherein the sensor is a temperature sensor.
 5. The covering element of claim 3, wherein the photo-electric layer comprises two electrically conductive layers and an ionically conductive layer between the two electrically conductive layers, the ionically conductive layer being adapted to have a flow of ions therein for setting up a voltage between the two electrically conductive layers.
 6. The covering element of claim 3, wherein the electro-magnetic radiation is light within the visible spectrum and the covering element, including the electro-chromatic layer and the photo-electric layer, is normally transparent to visible light.
 7. The covering element of claim 5, wherein the electrically conductive layers and the ionically conductive layer of the photo-electric layer are made from at least partially transparent materials.
 8. The arrangement of claim 5, wherein the means electrically connecting the photo-electric layer to the electro-chromatic layer comprise the electrically conductive layers of the photo-electric layer being electrically connected to the electrical control unit for providing electric energy to the control unit dependent upon the incident electro-magnetic radiation on the photo-electric layer.
 9. The covering element of claim 8, wherein the incident radiation on the ionically conductive layer in the photo-electric layer is adapted to establish an ion flow in that layer for establishing a voltage between the conductors of the photo-electric layer for supplying that voltage to the control unit which in turn supplies a voltage to the electro-chromatic layer for adjusting the ability of the electro-chromatic layer to pass incident electro-magnetic radiation through the electro-chromatic layer.
 10. The covering element of claim 5, wherein the electro-chromatic layer comprises a number of film layers arranged one upon the other and includes two electro-magnetic radiation transparent conductors, a second ionically conductive layer between the transparent conductors and a respective electro-chromatic electrode between each of the transparent conductors and the second ionically conductive layer that is between the transparent conductors; and the electro-chromatic layer being comprised of materials that are transparent to the electro-magnetic radiation.
 11. The covering element of claim 10, wherein the means electrically connecting the photo-electric layer to the electro-chromatic layer comprise the transparent conductors of the electro-chromatic layer being electrically connected to the electrical control unit so that the electrical control unit supplies a voltage to the transparent conductors and, through the electro-chromatic electrodes at the transparent conductors, supplies the voltage to the ionically conductive layer for changing the ionically conductive layer at the electro-chromatic layer in proportion to the voltage applied to it.
 12. The covering element of claim 11, wherein the means electrically connecting the photo-electric layer to the electro-chromatic comprise the electrically conductive layers of the photo-electric layer being electrically connected to the electrical control unit for providing electric energy to the control unit dependent upon the incident electro-magnetic radiation on the photo-electric layer.
 13. The covering element of claim 12, wherein the incident radiation on the ionically conductive layer in the photo-electric layer is adapted to establish an ion flow in that layer for establishing a voltage between the conductors of the photo-electric layer for supplying that voltage to the control unit which in turn supplies a voltage to the transparent conductors of the electro-chromatic layer for adjusting the ability of the electro-chromatic layer to pass incident electro-magnetic radiation through the electro-chromatic layer.
 14. The covering element of claim 1, wherein the photo-electric layer comprises two electrically conductive layers and an ionically conductive layer between the two electrically conductive layers, the ionically conductive layer being adapted to have a flow of ions therein for setting up a voltage between the electrically conductive layers.
 15. The covering element of claim 14, wherein the electro-chromatic layer comprises a number of film layers arranged one upon the other and includes two electro-magnetic radiation transparent conductors, a second ionically conductive layer between the transparent conductors and a respective electro-chromatic electrode between each of the transparent conductors and the second ionically conductive layer that is between the transparent conductors, and the electro-chromatic layer being comprised of materials that are transparent to the electro-magnetic radiation. 